Graphical Representation

I want to devise a series of graphs showing work done on a gym treadmill. The graph(s) would have 'slope' as the Y axis with 'time'(?) as the X axis and show inclines of say 10, 7.5, 5 and 2.5 degrees. A series of curves would span the graphs showing work done at a given speed. So for example the curves would show the equivalent of walking at 5k/hr on a 10 degree slope with the speed required to walk on the other inclines to give the same work. I realise I've left the weight of the walker out but once I figure out how to draw the graphs I could produce a set for various weights. Your thoughts please.